A computer may include a system Basic Input Output System (BIOS), also referred to as Read Only Memory (ROM) BIOS or system BIOS. The system BIOS includes programs that are executed for booting the computer when the computer is first powered on. The system BIOS may be stored in an onboard Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), flash memory, etc., on the motherboard of the computer. The inclusion of the system BIOS in a computer ensures that the even if the computer loses the contents of the main memory when the computer is powered down, the system BIOS can be used for booting the computer. The system BIOS may include code to control hardware components such as the keyboard, floppy drives, certain hard disk controllers, etc.
An option ROM may comprise firmware included on adapter cards that control bootable devices coupled to a computer. In certain architectures, option ROM may also be stored on the motherboard when a bootable device is included in the motherboard. Firmware located on one or more option ROMs may be called by the system BIOS while booting the computer, and the execution of the firmware on the one or more option ROMs may allow the computer to use the bootable devices corresponding to the one or more option ROMs, prior to the loading of the operating system. For example, an adapter card that controls a bootable device may include firmware that may be used to boot the device once the option ROM is loaded and executed by the ROM BIOS.